Infinite Warfare pre-order customers get early access to the Modern Warfare campaign a month before it launches in full.

Unfortunately, however, the offer isn't available on Xbox One or PC.

A PlayStation blog post has explained exactly how fans can download Modern Warfare Remastered, and who's eligible for codes.

"To gain access to the Call of Duty: Modern Warfare Remastered Campaign 30 days early, you must pre-purchase a PS4 edition of Call of Duty: Infinite Warfare that includes Modern Warfare Remastered," the post reads.

"If you have pre-ordered one of the above versions of the game at a participating retailer, you will need to complete your full purchase to be sent a PlayStation code by your retailer that will allow you access to the Modern Warfare Remastered campaign.

"Access to the Modern Warfare Remastered Campaign 30 days early is limited to PS4. Other current generation platforms and PC will be available on November 4, at which point the campaign and 10 multiplayer maps will be available.

"Once you receive your code, you can input it into your PS4 and begin downloading now. If you purchased through PlayStation Store, you will automatically be granted access and can also begin downloading now.

"This offer is good until November 3, and after that point you will need to install the full version of Modern Warfare Remastered that is included with your Call of Duty: Infinite Warfare Legacy Edition, Legacy Pro Edition, Digital Legacy Edition, or Digital Deluxe Edition.

"All of your campaign progress will carry over to the launch version, and you can continue wherever you left off."

The only bad news for fans of Modern Warfare Remastered is that they'll need the Infinite Warfare disc to play the game once it's released.

While this doesn't apply to the early access period, a Modern Warfare FAQ suggests that an Infinite Warfare disc will be needed to be inserted to access the content, despite the fact that it's a digital dpwnload.

This means that you would lose access to Modern Warfare Remastered if you sell Infinite Warfare when you're done.

PlayStation 4

"Call of Duty: Modern Warfare Remastered is a full game digital download that will be included in the Infinite Warfare Legacy Edition and Legacy Pro Edition on PlayStation 4. The digital download is redeemed via a voucher code on an insert in the box. The Infinite Warfare game disc must be inserted to play Modern Warfare Remastered. Internet connection is required."

Xbox One

"Call of Duty: Modern Warfare Remastered is included on the Infinite Warfare Xbox One disc (no voucher code required) in the Legacy Edition and Legacy Pro Edition of Infinite Warfare. Before Modern Warfare Remastered can be played, an additional download is required. The game disc must be inserted to play Modern Warfare Remastered. Internet connection is required."

Modern Warfare Remastered contains the original campaign, as well as ten classic multiplayer maps, including Crash, Backlot and Crossfire.

The full game with multiplayer maps and modes launches alongside Infinite Warfare in November.

It was recently revealed that Call of Duty Infinite Warfare would also have some form of early access on PS4, although Xbox One owners will also be able to take part in the pre-release multiplayer beta.